1. Field of the Invention
The present invention relates to a fastening body for fastening various kinds of sheet bodies to a mounting body and a product having the same fastening body, and, more particularly, to a fastening body having a molded fastener structure made of synthetic resin containing a plurality of male engaging elements for use for hanging a curtain, movie screen, back-out curtain, advertisement screen or the like on a hanging portion or for attaching interior materials such as various wall paper and carpet to various kinds of panels or attaching a cleaning body such as mop to a cleaner product.
2. Description of the Related Art
According to a conventionally proposed patent application, for example, when a curtain is attached to a curtain rail having a substantially C-shaped section, a belt-like fastening body for a curtain molded integrally with a flat substrate such that a plurality of synthetic resin male engaging elements like hooks are projected from a surface of the substrate is inserted and fixed to the curtain rail in the length direction thereof. Then, female engaging elements of a surface fastener provided along an upper edge of a curtain are engaged with the fastening body for the curtain having the male engaging elements, so that the curtain is attached to the curtain rail. As disclosed in Japanese Patent Laid-Open Publication No. 9-23906, such a fastening body is used not only for attaching the curtain but also for attaching an interior material such as various wall papers and carpet to various kinds of panels (wall, floor). Recently, the same fastening body has been also used for attaching, for example, a mop or the like to a cleaning tool, so that application field of the fastening body has been expanded.
Usually, the fastening body for use in a curtain or interior material is shaped in a tape which is rather long relative to the width thereof and a curtain rail on which that fastening body is to be attached is also long. Therefore, the fastening body is not attached by being inserted longitudinally, but, by pressing the fastening body against the engagement face of the curtain rail while bending it in the width direction, the right and left longitudinal edges of the fastening body are inserted into the engaging groove portions formed on both the ends in the width direction of the mounting body. Therefore, the fastening body is formed of material relatively likely to be elastically deformed and the flat substrate thereof is formed to be relatively thin. Further, the fastening body to be attached to the curtain rail as described above is demanded in a plane without being curved after it is attached to the curtain rail.
When the aforementioned fastening body is molded as described in FIG. 6 and a description of the aforementioned patent publication, for example, the entire fastening body is often curved in the width direction due to resin material used or thickness of the flat substrate after molding. Therefore, the cavity for molding the fastening body in a die is usually formed in a curved shape corresponding to a degree of the curve, extending in an opposite direction to that curve of the fastening body after molding, in order to keep the fastening body flat without being curved after molding.
On the other hand, the fastening body for use in a cleaning tool is rectangular and in order to prevent it from slipping out of a mounting body because of an external force exerted strongly, the flat substrate is thick and made of material having a relatively high rigidity. Thus, when the fastening body is mounted on the mounting portion of the cleaning tool, it cannot be curved easily unlike the aforementioned case. Thus, the fastening body is inserted into the engaging groove portions formed on the right and left side longitudinal edges of the mounting body and then, a cap is attached to each of both ends in the length direction of the mounting body so that the rectangular fastening body is secured from four sides.
Since conventionally the fastening body of this kind is flat like the fastening body for the curtain, the thickness of the flat substrate of the fastening body is set to substantially the same dimension as a groove width of the engaging groove portion of the mounting body, in order to mount the fastening body onto the mounting body without any clearance. For this reason, the fastening body is very hard to insert into the engaging groove portion of the mounting body.
Thus, in a recent mounting body such as a cleaning mop, the groove width of the engaging groove portion is set larger than the thickness of the fastening body so as to facilitate insertion of the fastening body into the engaging groove portions. Further, plural protruded rows are provided to extend longitudinally on a bottom face which comes into contact with a rear face of the fastening body except the engaging groove portions of the mounting body. Further, the flat substrate of the fastening body is molded such that a side thereof in which the engaging elements are projected is curved so as to be protruded outward. In this case, when the fastening body is inserted into the engaging groove portions, the fastening body does not interfere with the protruded rows. Since this fastening body has a large thickness and high rigidity, it is never deformed or curved after the molding. In order to obtain a curved shape after the molding as described above, it is necessary to form the molding cavity itself in a curved shape.
Such a structure of the mounting body and fastening body is preferable at the time of cleaning, for the cleaning tool, in addition to the aforementioned function. That is, this kind of the cleaning mop is pressed strongly against a floor surface during cleaning and slid violently on the same floor. As a result, when the aforementioned structure is employed, the mop is pressed strongly against the mounting body through the fastening body. By this pressing, the fastening body curved in the width direction is deformed so that it becomes a flat shape. As a result, the both ends in the width direction of the fastening body is pressed strongly to the open wall faces of the engaging groove portions of the mounting body, thereby effectively preventing the fastening body from being removed from the mounting body.
However, not only the fastening body disclosed in the previously mentioned patent application but also the fastening body to be attached to the cleaning tool is desired to be molded so as to be positively curved although the purposes thereof are different. Particularly, improvement of molding technology for this kind of products enables continuous molding of this kind of the fastening body. As a typical molding method, a die wheel having a plurality of cavities for molding engaging elements for a surface fastener on a peripheral face thereof is rotated in a single direction and molten resin is introduced to the peripheral face. As a result, the engaging elements are formed and a flat substrate having a desired thickness is formed integrally. After cooling, that molded product is separated from the wheel surface.
If it is intended to form the flat substrate positively in a curved shape as described above when this molding method is used, the aforementioned die wheel needs to be formed such that the central portion of the body is recessed or projected. Because usually the die wheel is constructed by overlaying a plurality of ring-like thin circular plates, not only a high precision is demanded for that manufacturing but also the manufacturing cost is high.
In case of the fastening body for curtain or the like formed of a single resin material, having a relatively small thickness, when molding condition for resin material, thickness and the like is changed, the curvature of a curved face after molding is changed. Thus, the curvature of the cavity for molding the flat substrate cannot be set constant.
Accordingly, the present invention has been achieved to solve the above described conventional problem, and therefore, an object of the invention is to provide a fastening body made of synthetic resin formed without carrying out a special processing on a molding die such that it is curved with a desired curvature in the width direction, the fastening body holding a sheet-like body, and a product having the same fastening body.
The above object is achieved by the present invention effectively.
According to the present invention, there is provided a fastening body made of synthetic resin to be fixed by engagement in each of engaging groove portions of a mounting body having a substantially U-shaped section, formed along both side edges in a width direction so that openings thereof oppose each other, so as to attach various sheet-like bodies thereto, wherein the fastening body has a flat substrate having a thickness substantially the same as a groove width of the engaging groove portion and edge portions to be engaged in the engaging groove portions on both side edges in a width direction and a plurality of male engaging elements of a surface fastener, projected integrally from a surface between the edge portions of the flat substrate, and the flat substrate is comprised of two synthetic resin layers having different molding shrinkage rates.
The flat substrate of the fastening body is molded integrally with the engaging elements and is comprised of two layers, front and rear layers, using two kinds of synthetic resin materials having different molding shrinkage rates. Upon this molding, the cavities for molding the fastening body does not need to be formed intentionally in a curved configuration, however, it is formed on the same plane.
That is, when the fastening body for a cleaning mop is formed continuously by means of the aforementioned die wheel, the same die wheel does not need to be formed such that the central portion thereof is dented or projected. This has only to be formed in an ordinary cylinder. The fastening body is made of resin material having a relatively high rigidity and has a larger thickness than the fastening body for curtain or the like. Therefore, when the fastening body is peeled off the die wheel after completion of molding, synthetic resin layer having a higher molding shrinkage rate is contracted more than synthetic resin layer having a lower molding shrinkage rate so that the fastening body is curved in the width direction with a desired curvature based on a difference in the contraction.
When the fastening body is used as a fastening body for the curtain or interior material, it is curved after molding in most cases. Therefore, a synthetic resin layer having a high molding shrinkage rate is disposed on a side by which the curve occurs so as to allow the fastening body to be curved in a direction opposite to the direction of the curve caused by the molding. In this case also, the peripheral face of the die wheel is a mere cylinder, so that, after molding, the fastening body is formed in a flat plane without being curved in the width direction.
Although, as a typical molding method therefor, continuous molding method using the die wheel as described may be employed, it is permissible to use an ordinary injection molding. Typical continuous molding methods will be described.
A plurality of cavities for molding engaging elements are formed in a peripheral face of the die wheel and the die wheel is driven in a single direction. Molten resin extruding dies are disposed upstream and downstream in the rotation direction of the peripheral face of the die wheel such that they oppose the peripheral face of the die wheel. Molten resin of a predetermined width is introduced continuously to the peripheral face of the die wheel from each of the extruding dies under a predetermined resin pressure. A part of molten resin introduced to the upstream is filled in the male engaging elements cavities so as to form the engaging elements and a first layer of the flat substrate having a predetermined thickness is continuously formed with remaining of the same molten resin on the peripheral face of the die wheel. Molten resin introduced to the downstream joins the first layer of the flat substrate so that a second layer is formed integrally.
When synthetic resin materials to be extruded from the aforementioned extruding dies are materials having different molding shrinkage rates, synthetic resin layer formed of a material having a higher molding shrinkage rate is contracted more in the width direction than the other synthetic resin layer to make a curve. The curvature at this time is determined by a difference of molding shrinkage rate between synthetic resin layers. Therefore, a fastening body having a desired curvature in the width direction is formed by selecting material.
To provide with a predetermined flexibility to the flat substrate and facilitate correction of the curvature of such curved configuration, continuous or incontinuous concave grooves are formed between plural male engaging elements along the length direction or the width direction of the flat substrate surface or dented portions are formed intermittently along the engaging edge portions of the flat substrate which engage into the engaging groove portions of the mounting body. Alternatively, the aforementioned engaging edge portion may be formed partially in a wedge shape such that its thickness decreases as it goes toward outside.
Preferably, the synthetic resin layer of the flat substrate disposed on a side from which the engaging elements project is formed of synthetic resin material having a higher molding shrinkage rate than the synthetic resin layer disposed on a side opposite to the side from which the engaging elements project. As a result, in the fastening body after molding, the projection side of the engaging elements is curved so that it is recessed in the width direction. This is preferable for forming a flat shape fastening body having flexibility and a relatively small thickness, which may be applied to fasten a curtain or the like. This fastening body is used by being fitted in a curtain rail.
Alternatively, the synthetic resin layer of the flat substrate disposed on a side from which the engaging elements project is formed of synthetic resin material having a molding shrinkage rate lower than the synthetic resin layer disposed on a side opposite to the side from which the engaging elements project. In this case, to the contrary of the fastening body of the previous paragraph, the fastening body is curved such that the projection side of the engaging elements is protruded in the width direction. Therefore, this is preferable for molding a curved fastening body, which may be applied to fasten the mop or the like. This fastening body is used as being fixed by engagement onto a cleaning tool.